1. Field of the Invention
This invention relates generally to bicycles, and more particularly to high performance light weight bicycles expected to be subjected in off-road racing and the like to extreme and repeated frontal and drop off impacts against the front wheel, although it may be applicable to other bicycles, such as those intended primarily for street use.
2. Description of the Prior Art
Such prior art bicycles customarily employ a light weight frame in order to enable a rider to attain maximum speed, which includes a head tube 11, as shown in FIG. 7, and top and bottom tubes 12 and 13 secured at their forward ends thereto. When a frontal impact occurs, members 12 and 13 are most affected. Such impact is represented in FIG. 7 as force F.sub.h which imparts a bending force to members 12 and 13 that is most severe immediately rearward of their junctures with head tube 11 in the areas designated X and Y. Under such bending force, each of those members is subjected to a tensile strain on its upper portion and a compression strain on its lower portion as illustrated in FIG. 8.
When the bicycle is ridden over a drop off, force F.sub.v (FIG. 7) imparts a bending force to members 12 and 13 which is the reverse of that from F.sub.h so, as shown in FIG. 9, the upper portions in the areas X and Y are under a compressive strain and the lower portions thereof are subjected to a tensile strain.
Severe and numerous repetitions of such occurrences have caused failure of such light weight frames in the areas X and/or Y. While the incidence of failure may be reduced by adding a gusset adjacent those X, Y areas and secured to the members 11, 12 and 13, that merely shifts those highly stressed areas rearwardly and adds weight that is objectionable in high performance light weight bicycles.